During a surgical operation, the surgical site and surrounding areas must remain sterile. A “surgical field” is an environmentally-controlled area in a typical hospital operating room where the risk of infection, such as from naturally occurring organisms (e.g., bacteria), is minimized or eliminated. The sterility of the surgical field is typically controlled by limiting the introduction of infection-causing bacteria and other contaminants. In general, this is achieved by implementing strict regulations over the personnel and equipment present in the operating room.
Surgical drapes are often utilized during surgery in the operating room to minimize the risk of infection to surgical patients and to protect medical equipment from the surgical field. An array of different surgical drapes may be placed over the patient and the medical equipment to create a sterile barrier, preventing microorganisms and other contaminants that may cause infections from migrating to and from exposed tissue, bodily fluids, etc. For example, bodily fluids secreted during surgery that would otherwise settle on medical equipment, which would then become contaminated and potentially hazardous, will instead ultimately settle on the drapes and not on the draped medical equipment.
Optical devices, such as surgical microscopes and cameras, have become an integral part of many operating rooms. Microscopes used for surgery are generally permanent fixtures of the operating room, typically mounted to the ceiling or a wall, or supported on a floor-mounted stand. Surgical microscopes often have an articulated cantilever support arrangement to facilitate movement of the microscope over an operating zone. Surgical microscopes normally take on very complex shapes, often having several sets of eyepieces that permit the surgeon and others to simultaneously view the magnified area under the microscope's objective lens. In addition to the ocular segments, one or more viewing tubes and/or laser arms (depending on design) project out from the microscope housing.
Due to its complex geometry, it is very time consuming and difficult to thoroughly sterilize an entire microscope assembly before and after each surgical procedure. As such, it is common practice to cover the microscope with a disposable surgical drape. The drape typically comprises a flexible sheet-form material that covers all of the components of the surgical microscope, including the ocular ports, the viewing tubes, the microscope head, and the structure that supports the head. The disposable surgical drape is typically manufactured and packaged under sterile conditions so that, when unpackaged and placed on a microscope, the drape creates a sterile field around the microscope and its components.
The microscope drape is often initially affixed to the microscope at the lens housing for the objective lens, to orient the drape with respect to other structure of the microscope. For example, some microscope drapes include an annular positioning sleeve that is attached to or integral with an elongated tubular cover. The positioning sleeve fits onto the objective lens housing of the microscope to initially affix the sterile drape to the microscope assembly. Once the surgical drape is attached to the objective lens housing, the remaining portions of the drape can be conveniently unfolded and positioned to cover the remainder of the microscope assembly.
In order to protect the objective lens without obstructing the view of the surgical area, a transparent protective lens (also referred to in the art as “lens cover”) adapted to shield the objective lens is usually associated with the drape assembly. For example, in some prior art configurations, a housing comprising a rigid mounting ring, which encloses a transparent-plastic lens, is integrally-formed with the drape. The mounting ring housing is adapted to attach, typically via a separate adaptor or clamp, to the outer diameter of the microscope objective lens housing. Some designs incorporate an interchangeable lens cover that can be removed from the lens cover housing and replaced with a substitute lens cover.
Unlike typical microscopes, the illuminating light source of many surgical microscopes comes from above and shines onto the lens cover covering the objective lens, which may generate glare when the surgeon looks through the microscope. Moreover, during surgical operations, the lens cover can be splattered by fluids from the surgery, such as blood, which will obscure the surgeon's vision. To rectify this problem, someone on the surgical team is conventionally required to either wipe the lens cover (which can further obscure the vision), remove and replace the lens cover (which requires a lens cover be taken from another drape assembly), or replace the entire drape (which temporarily breaks the sterile field, is time consuming, and wastes another entire drape assembly). Finally, different surgical microscopes use different size objective lenses. Thus, a facility with a variety of different surgical microscopes is required to carry an array of different surgical drape assemblies with lens housings and lens covers of various sizes, increasing overhead costs and unnecessarily complicating the preparation process for the operating room.